1. Field of the Invention
The present invention relates to the storage of heat or cold in substantial quantities over relatively long periods of time.
2. Prior Art
With the recent emphasis on use of solar heat, in particular, the problems associated with storing such heat for use at a later time have become more apparent. The high cost of construction of storage devices has minimized the effectiveness and utility of solar heat. Likewise, storage of heat from any source as well as the storage of "cold" or negative heat has been a problem. In general, large volumes of storage media are absolutely essential, and at the present time the costs of providing storage devices of adequate size has proved to be a limiting factor.
In the prior art, the use of solid heat or cold storage media has been known. Likewise, in-ground storage, where the ground itself has been used for heat or cold storage is shown in U.S. Pat. No. 3,262,493, where ducts are buried directly into the ground. The undisturbed earth around the ducts is used for heat or cold storage. Thus, high cost duct work is provided in the ground, which is expensive to install and also to maintain. A liquid is used for heat exchange, raising the costs of construction even further.
The use of rock as a storage medium is shown in U.S. Pat. No. 2,680,565. A separate chamber inside a room or bin within the home being heated is used for the rock.
Other devices utilizing solid material heat storage media are shown in U.S. Pat. No. 3,369,541 and 3,412,728. These patents are believed to be typical of many others which use stones or sand within chambers or bins for heat storage.
In some cases, one is concerned that internal circulation should not happen, such as a case where rocks in one end of a channel are hot and are cold in the other end. This is known and a preventative measure is known, of circulating the air vertically, as described in Solar Energy Thermal Processes by Duffie, J. A., & Backman, W. A., John Wiley & Sons, Inc., 1974, p. 227-228.